The present invention relates to a ventilated umbrella, especially to an umbrella that when the umbrella is stretched, the upper circumference of the lower canopy is stretched by a plurality of strings so that the lower canopy and the upper canopy are separated for ventilation. When being folded, the lower canopy is smoothed by the strings so that the upper and the lower canopies are convenient to roll up.
There are various designs of foldable umbrellas with functions of windproofing/ventilation, as disclosed by U.S. Pat. No. 2,522,645, U.S. Pat. No. 3,032,047, U.S. Pat. No. 4,979,534, U.S. Pat. No. 5,368,055, U.S. Pat. No. 5,487,401, U.S. Pat. No. 5,890,506, U.S. Pat. No. 6,006,769, U.S. Pat. No. 6,039,063, U.S. Pat. No. 6,155,278, U.S. Pat. No. 6,167,894, U.S. Pat. No. 6,170,499, U.S. Pat. No. 6,250,319, U.S. Pat. No. 6,202,662, U.S. Pat. No. 6,397,867 and so on. Refer to U.S. Pat. No. 6,167,894, U.S. Pat. No. 6,170,499, U.S. Pat. No. 6,250,319, U.S. Pat. No. 6,202,662, U.S. Pat. No. 6,397,867, a foldable umbrella frame composed by a plurality of ribs, stretchers and a surface. The surface having a plurality of sectors separated by a plurality of stretchers. An upper canopy is disposed on upper surface of the umbrella while a lower canopy is arranged on lower surface of the circumference of the upper canopy. The lower circumference of the upper canopy is overlapped with the upper circumference of the lower canopy. By a plurality of strings with or without elasticity that one end is connected with the upper circumference of the lower canopy and the other end is connected with a fixed/sliding notch/ring on a shaft, the lower canopy is pulled down or the rear end of the shaft is pulled so as to achieve purposes of ventilation/windproofing. However, most of umbrellas only has function of ventilation/windproofing after being pulled out fully, the convenience of usage after being folded is neglected.
Refer to U.S. Pat. No. 6,397,867, from FIG. 1 to FIG. 6, the disadvantages of conventional umbrellas are as followings:    (1) After being folded, due to the change of relative position (angle) between the string P1 and the stretcher P2, the connecting point P5 for string on upper circumference P4 of the lower canopy P3 is loose and saggy, as shown in FIG. 4. Thus there is ridge and knot between the upper canopy P6 and the lower canopy P3. Once the lower canopy P3 is curled into the upper canopy P6, it's inconvenient for users to roll up the canopy as well as unfold the umbrella.    (2) In order to avoid the drooping of the upper circumference P4 of the lower canopy P3, the overlapping area P7 between the upper and the lower canopies P6, P3 need to broaden. And the string P1 connects to the connecting point P5 that is above a horizontal line formed by joints P9 (the position of the stretcher P2 for supporting the main rib P8), as shown in FIG. 1, 2, & 3. This needs more umbrella clothes and the cost is increased. Moreover, the increase of overlapping area makes the ventilated resistance also raise so that the ventilation effect is poor.    (3) As shown in FIG. 4, conventional notched ring P10, rear end P11 of the string is mounted inside the notched ring P10, refer to FIG. 5, this is difficult to assemble and the rear end of the string can't be fixed and easy to move or fall off while being stretched or folded. Another notched ring P12, as shown in FIG. 6, the rear end P11 of the string is inserted into the notched ring P12 through an opening P13 and then a cap P14 is covered on the opening P13 of the notched ring P12 so as to prevent the string from falling off. This makes the structure of the umbrella more complicated and the cost is increased so that it is difficult to be mass-produced.